1. Field of the Invention
The present invention relates to an image sensor and an LED print head that are used in image input devices, image writing devices, etc. In particular, the invention relates to a long contact image sensor incorporating a rod lens array.
2. Description of the Related Art
An image sensor incorporating a rod lens array that is interposed between first and second frames is disclosed in FIG. 1 of JP-A-2002-218159 as a device incorporating a rod lens array.
Further, a writing device in which three rod lenses are packaged integrally by a package case and a device body is disclosed in FIG. 1 of JP-A-2001-150729.
In FIG. 1 of JP-A-2002-218159, reference numeral 1 denotes an image sensor; 2, a glass plate, 3; a frame, 6; light sources; 8, a rod lens array consisting of a plurality of rod lenses arranged in one direction; 9, light-receiving elements; 10, a sensor substrate; and 18, an original document. The rod lens array 8 has only a single rod lens array extending in the one direction.
In FIG. 1 of JP-A-2001-150729, reference numeral 1 denotes a light-emitting element array substrate; 2, a light-emitting element array; 3A–3C, rod lens arrays; 4, a package case; 5, a device body; and 8, connecting members. Although the three rod lens arrays 3A–3C extend in one direction, they have overlap regions that overlap with each other perpendicularly to the array extending direction and hence do not form a single straight line (i.e., one-dimensional arrangement).
In the above-configured conventional image sensor, the rod lens array of the image sensor is a single rod lens array whose length corresponds to a reading width. Therefore, in designing a long image sensor, it is necessary to use a dedicated rod lens array whose length suits an intended reading width. A problem arises that such a rod lens array should necessarily be expensive.
Although the conventional long writing device employs the plurality of rod lens array, writing lines do not have a one-dimensional arrangement. Rod lenses close to each other of adjoining rod lens arrays produces different image forming positions, electrical corrections for positional deviations between the image writing lines are needed in writing.